Circular stapling device with buttress

ABSTRACT

The cartridge assembly includes a housing, a pusher member, a fastener cartridge body, a circular cartridge buttress member, and a retaining ring member. The pusher member is supported within the housing and movable between a first position and a second position. The fastener cartridge body is supported on the housing and has a tissue engaging surface that extends to an annular edge. One or both of the housing and the fastener cartridge body define an annular containment groove. The circular cartridge buttress member has a body portion and an extension portion. The body portion is supported on the tissue engaging surface of the fastener cartridge body. The extension portion extends from the body portion and over the annular edge of the tissue engaging surface. The retaining ring member is secured within the containment groove to releasably secure the extension portion of the circular cartridge buttress member to the cartridge assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 61/768,661, filed Feb. 25, 2013, the entiredisclosure of which is incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to surgical stapling devices and, moreparticularly, to structures and methods for removably attaching buttressmaterial to circular surgical stapling devices for use in anastomosisprocedures.

BACKGROUND

Fasteners have traditionally been used to replace suturing when joiningvarious body structures such as, for example, the bowel or bronchus.Surgical stapling devices employed to apply these fasteners aregenerally designed to simultaneously cut and seal tissue to reduce thetime and risks involved with anastomosis procedures.

Circular surgical stapling devices are employed by surgeons tosequentially or simultaneously apply one or more surgical fasteners,e.g., staples or two-part fasteners, to body tissue for the purpose ofjoining segments of body tissue together and/or for the creation ofanastomoses. Circular surgical stapling devices generally include anannular fastener cartridge assembly that supports a plurality of annularrows of fasteners, an annular anvil assembly operatively associated withthe fastener cartridge assembly which provides a surface against whichthe fasteners are formed upon a firing of the circular stapling device,and an annular blade for cutting tissue.

For most procedures, the use of bare fasteners, with the fasteners indirect contact with the patient's tissue, is generally acceptable. Theintegrity of the tissue will normally serve to prevent the fastenersfrom tearing out of the tissue and compromising the sealing beforehealing has occurred. However, in some surgical operations buttressmaterials are employed by surgeons in combination with circular staplingdevices to bridge, repair and/or reinforce tissue defects within apatient. In particular, buttress materials reduce the trauma suffered bythe patient, reduce the instances of leakage, reduce the instances ofbleeding, and create a relatively strong bond between adjacent bodytissues.

Accordingly, there is a need for reliably and removably attachingbuttress material onto a circular stapling device so that the buttressmaterial does not interfere with the operation of the device, remains onthe device until after the fasteners are fired, and is convenient andeasy to install and use.

SUMMARY

According to one aspect, a circular stapling device includes a handleassembly, an elongate body that extends from the handle assembly, acartridge assembly mounted on a distal end of the elongate body, acircular cartridge buttress member, a retaining ring member, and a knifeassembly.

The cartridge assembly defines an annular containment groove andincludes a housing, a pusher member, and a fastener cartridge body. Inembodiments, the housing and the fastener cartridge body together definethe containment groove therebetween. The pusher member is supportedwithin the housing and is movable between a first position and a secondposition. The fastener cartridge body is supported on the housing andhas a tissue engaging surface that extends to an annular edge.

The circular cartridge buttress member has a body portion and anextension portion. The body portion is supported on the tissue engagingsurface of the fastener cartridge body. The extension portion extendsfrom the body portion and over the annular edge of the tissue engagingsurface.

The retaining ring member is secured within the containment groove overthe extension portion of the circular cartridge buttress member toreleasably secure the circular cartridge buttress member to the fastenercartridge body. In embodiments, the retaining ring member is an o-ring.The o-ring is formed of an elastomeric material.

The knife assembly includes a primary knife blade and a secondary knifeblade. The primary knife blade is dimensioned to cut tissue. Thesecondary knife blade is connected to the pusher member. The secondaryknife blade is movable with the pusher member to cut the retaining ringmember and relieve a tension that the retaining ring member exerts onthe extension portion of the circular cartridge buttress member. Thetension is sufficient to maintain the circular cartridge buttress membersecured to the fastener cartridge body.

The fastener cartridge body supports a stop member that defines areceiving channel dimensioned to receive the retaining ring member and aknife slot dimensioned to receive a distal end portion of the secondaryknife blade. The stop member includes a cross member dimensioned toprevent tissue from extruding in front of the distal end portion of thesecondary knife blade. The distal end portion of the secondary knifeblade is engageable with the cross member upon a translation of thedistal end portion of the secondary knife blade through the knife slot.In embodiments, the stop member is formed of a polyethylene material.

The housing includes one or more containment tabs that extends distallyfrom a distal end portion of the housing so that an inner surface of theone or more containment tabs are engageable with an outer surface of theretaining ring member to maintain the retaining ring member secured tothe housing after the retaining ring member is cut with the secondaryknife blade.

In accordance with another aspect, a cartridge assembly includes ahousing, a pusher member, a fastener cartridge body, a circularcartridge buttress member, and a retaining ring member. The cartridgeassembly further includes a tissue cutting knife blade dimensioned tocut tissue.

The pusher member is supported within the housing and is movable betweena first position and a second position.

The fastener cartridge body is supported on the housing and has a tissueengaging surface that extends to an annular edge. One or both of thehousing and the fastener cartridge body define an annular containmentgroove.

The circular cartridge buttress member has a body portion and anextension portion. The body portion is supported on the tissue engagingsurface of the fastener cartridge body. The extension portion extendsfrom the body portion and over the annular edge of the tissue engagingsurface.

The retaining ring member is secured within the containment groove toreleasably secure the extension portion of the circular cartridgebuttress member to the cartridge assembly. In embodiments, the retainingring member is an o-ring formed of elastomeric material.

A knife blade is connected to the pusher member. The knife blade ismovable with the pusher member to cut the retaining ring member andrelieve a tension that the retaining ring member exerts on the extensionportion of the circular cartridge buttress member. The tension issufficient to maintain the circular cartridge buttress member secured tothe fastener cartridge body.

The fastener cartridge body supports a stop member that defines areceiving channel dimensioned to receive the retaining ring member and aknife slot dimensioned to receive a distal end portion of the knifeblade. The stop member includes a cross member dimensioned to preventtissue from extruding in front of the distal end portion of the knifeblade. The distal end portion of the knife blade is engageable with thecross member upon a translation of the distal end portion of the knifeblade through the knife slot. In embodiments, the stop member is formedof a polyethylene material.

The housing includes one or more containment tabs that extend distallyfrom a distal end portion of the housing so that an inner surface of theone or more containment tabs are engageable with an outer surface of theretaining ring member to maintain the retaining ring member secured tothe housing.

According to yet another aspect, the present disclosure is directed to amethod for releasing a cartridge buttress member from a cartridgeassembly of a circular stapling device. The method involves providing acircular stapling device including an elongate member having a cartridgeassembly mounted on a distal end of the elongate body. The cartridgeassembly defines a containment groove and includes a retaining ringmember and a cartridge buttress member. The cartridge buttress memberhas a body portion and an extension portion. The retaining ring memberis disposed within the containment groove over the extension portion tosecure the body portion on a tissue engaging surface of the cartridgeassembly. The method includes cutting the retaining ring member torelease the cartridge buttress member from the circular stapling device.

When the circular stapling device includes a knife blade secured to apusher member supported within the cartridge assembly, the methodinvolves the step of moving the knife blade by moving the pusher membersuch that the knife blade cuts the retaining ring member. One stepincludes preventing tissue from extruding in front of the knife blade.One step involves relieving a tension that the retaining ring memberexerts on the extension portion of the circular cartridge buttressmember. The method includes cutting tissue with another knife blade.

Other aspects, features, and advantages will be apparent from thedescription, drawings, and claims.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the disclosureand, together with a general description of the disclosure given aboveand the detailed description given below, serve to explain theprinciples of the disclosure, wherein:

FIG. 1 is a perspective view of a circular surgical stapling deviceaccording to the present disclosure;

FIG. 2 is an enlarged perspective view of a cartridge assembly of thecircular stapling device of FIG. 1;

FIG. 3A is a perspective view, with parts separated, of the cartridgeassembly shown in FIG. 2;

FIG. 3B is an enlarged perspective view of a stop member of thecartridge assembly of FIGS. 2 and 3A;

FIG. 4 is an enlarged, longitudinal, cross-sectional view of thecartridge assembly of FIGS. 2 and 3A shown in a first configuration;

FIG. 5A is an enlarged, longitudinal, cross-sectional view of thecartridge assembly of FIGS. 2 and 3A shown in a second configurationwith a distal portion of a knife of the presently disclosed circularsurgical stapling device shown being distally advanced through thecartridge assembly; and

FIG. 5B is an enlarged view of the indicated area of detail shown inFIG. 5A.

DETAILED DESCRIPTION

As used herein, the term “clinician” refers to a doctor, a nurse, or anyother care provider and may include support personnel. Particularembodiments of the present disclosure will be described herein withreference to the accompanying drawings. As shown in the drawings and asdescribed throughout the following description, and as is traditionalwhen referring to relative positioning on an object, the term “proximal”refers to the end of the device that is closer to the clinician and theterm “distal” refers to the end of the device that is farther from theclinician. In the following description, well-known functions orconstructions are not described in detail to avoid obscuring the presentdisclosure in unnecessary detail.

Referring initially to FIG. 1, a circular surgical stapling device foruse with a buttress material is disclosed herein and is generallydesignated as 10. In embodiments, the surgical stapling device 10 isadapted for reuse and in certain embodiments; the surgical staplingdevice 10 is adapted for a single use and can be disposable.

Reference may be made to U.S. Pat. No. 5,915,616 to Viola et al. andcommonly owned U.S. Patent Application Publication No. 2011/0174099,filed on Nov. 15, 2010, entitled “Adapters for Use Between SurgicalHandle Assembly and Surgical End Effector,” the entire contents of whichare incorporated herein by reference, for a detailed discussion of theconstruction and operation of exemplary circular stapling devices.

The surgical stapling device 10 includes a handle assembly 20, a tubularelongate body 30, an end effector 40, and a knife assembly 50. Thehandle assembly 20 includes a rotatable advancing member 22 and apivotable trigger member 24 that are operatively coupled to one or moredrivers supported by the surgical stapling device 10. The elongate body30 extends distally from a distal end portion of the handle assembly 20to a proximal end portion of the end effector 40 so that the elongatebody 30 is disposed between the handle assembly 20 and the end effector40. In some embodiments, the elongate body 30 has a linear shape alongthe length of the elongate body 30, and in certain embodiments, theelongate body 30 has a curved shape along the length of the elongatebody 30.

The end effector 40 includes a fastener cartridge assembly 100 and ananvil assembly 200. Notably, the fastener cartridge assembly 100 and/orthe anvil assembly 200 may be replaced and the circular stapling device10 may be reused.

With reference to FIG. 5A, the knife assembly 50 is supported within theend effector 40 and includes a substantially cylindrical knife blade 52adapted to sever tissue and a secondary knife blade 170 adapted tosevere a retaining ring member 140 that secures a cartridge buttressmember 130 to a cartridge body 120 of the cartridge assembly 100, aswill be described in greater detail below. In embodiments, the retainingring member 140 is an o-ring, a tie, a band, or a suture. Inembodiments, the retaining ring member 140 is formed of an elastomericmaterial.

The circular stapling device 10 can include any number of drivers toeffectuate a firing of the stapling device 10 including, for example, afirst driver that is operable to effectuate the firing and formation offasteners 60 (see FIGS. 4 and 5) supported by the end effector 40 and/orthe severance of the retaining ring member 140, and second driver thatis operable to advance the cylindrical knife blade 52 separate and/orindependent of the first driver. Alternatively, a single driver may beused to fire and form the fasteners 60, and to advance one or both thecylindrical knife blade 52 and the secondary knife blade 170.

Turning now to FIGS. 2-5B, the fastener cartridge assembly 100 ismounted on a distal end portion of the elongate body 30. The fastenercartridge assembly 100 includes a housing 110, a fastener cartridge body120, a circular cartridge buttress member 130, a retaining ring member140, a stop member 150, a pusher member 160, and a secondary knife blade170.

With reference to FIG. 3A, the housing 110 includes a shell body 112having a plurality of fingers 114 extending around a distal end portionof the shell body 112. At least some of the plurality of fingers 114define an opening 114 a therethrough, and at least some of the pluralityof fingers include a containment tab 114 b that extends distally from adistal end portion of the respective fingers 114. The containment tabs114 b are dimensioned to maintain the retaining ring member 140 securedto the housing 110 after the retaining ring member 140 is cut by thesecondary knife blade 170, as described in greater detail below.

With reference to FIG. 4, a radial or annular containment groove 118 isdefined between a proximal surface of the fastener cartridge body 120and a distal end portion of the shell body 112 such that the housing 110and the fastener cartridge body 120 together define the annularcontainment groove 118 therebetween. The containment groove 118 extendsradially along an inner surface of each containment tab 114 b and isdimensioned to receive the retaining ring member 140.

The containment groove 118 is defined by a chamfer extending radiallyaround the periphery of a distal-most rim or edge of the shell body 112.Each finger 114 is defined by a pair of longitudinally extendingelongate slots 116 that are defined in a distal end portion of the shellbody 112.

The distal end portion of the housing 110 is dimensioned to receive thecartridge body 120 therein.

The cartridge body 120 is supported on the housing 110 and includes atissue engaging surface 122 that extends to an annular edge 122 a anddefines a plurality of fastener retaining slots 124 in an annular and/orconcentric array about the tissue engaging surface 122. Each fastenerretaining slot 124 is dimensioned to support a fastener 60 (FIG. 4) suchas a surgical staple. The cartridge body 120 includes a sidewall 126having a plurality of radially spaced detents 126 a extending radiallyoutward from an outer surface of the sidewall 126. Each detent 126 a isdimensioned to be received within one of the plurality of openings 114 adefined in the fingers 114 of the housing 110 to secure the cartridgebody 120 to the distal end portion of the housing 110 when the cartridgebody 120 is positioned in the distal end portion of the housing 110. Astop member support 128 radially extends from the outer surface of thesidewall 126. Stop member support 128 is dimensioned to secure the stopmember 150 to the cartridge body 120.

The cartridge buttress member 130 has a body portion 132 and anextension portion 134 that extends from the body portion 132 of thecartridge buttress member 130. In use, the body portion 132 is supportedon the tissue engaging surface 122 of the cartridge body 120. Also inuse, the extension portion 134 is dimensioned to extend over the annularedge 122 a of the tissue engaging surface 122 of the cartridge body 120and against an outer surface of the housing 110.

As seen in FIG. 2, with extension portion 134 of cartridge buttressmember 130 extending against the outer surface of the housing 110, theretaining ring member 140 may be positioned around the outer surface ofthe extension portion 134, along the inner surface of the containmenttabs 114 b of the housing 110, and within the radial containment groove118 to secure the extension portion 134 of the cartridge buttress member130 to the cartridge assembly 100. In so doing, the retaining ringmember 140, together with the containment tabs 114 b and the grooves 118of the housing 110 function to maintain the body portion 132 of thecartridge buttress member 130 against the tissue engaging surface 122 ofthe cartridge body 120, as illustrated in FIG. 2.

The retaining ring member 140 is secured within the containment groove118 over the extension portion 134 to releasably secure the circularcartridge buttress member 130 to the fastener cartridge body 120.

The stop member 150 is securable to the cartridge body 120 and isdimensioned to be received by the stop member support 128 of thecartridge body 120. In embodiments, the stop member 150 is formed of apolyethylene material. As seen in FIG. 3B, the stop member 150 includesstop member body 152 that defines a ring receiving channel 154therethrough. The ring receiving channel 154 is dimensioned to receivethe retaining ring member 140 and secure the retaining ring member 140within the ring receiving channel 154. The stop member body 152 definesa knife slot 156 dimensioned to receive a distal end portion of thesecondary knife blade 170 and a cross member 158 dimensioned to limitdistal advancement of the secondary knife blade 170 and prevent tissuefrom extruding in front or distal of the secondary knife blade 170, aswill be described in greater detail below. The knife slot 156 is definedin the stop member body 152 in a direction substantially traverse to thering receiving channel 154.

The pusher member 160 includes a substantially cylindrical body 162having a plurality of distally extending pushers 162 a. The plurality ofpushers 162 is disposed in an annular and/or concentric array about thecylindrical body 162 of the pusher member 160. The pusher member 160defines a knife supporting slot 162 b dimensioned to receive a supportarm 174 of secondary knife blade 170 to secure the secondary knife blade170 to the cylindrical body 162 of the pusher member 160. As seen inFIGS. 4 and 5A, a pair of opposed nubs 164 extend from the cylindricalbody 162 into the knife supporting slot 162 b. An inner surface of thecylindrical body 162 defines a central opening 162 c dimensioned toreceive the cylindrical knife 52 therethrough (see FIG. 5A).

The pusher member 160 is movably supported within the housing 110 and isoperatively coupled to a driver adapted to drive the pusher member 160through the housing 110 between a proximal position and a distalposition to dispense the fasteners 60 retained in the fastener retainingslots 124 of the cartridge body 120 and to distally drive the secondaryknife blade 170 to severe the retaining ring member 140 upon a firing ofthe circular stapling device 10.

The secondary knife blade 170 is connected to the pusher member 160 andmovable with the pusher member 160 to cut the retaining ring member 140and relieve a tension that the retaining ring member 140 exerts on theextension portion 134 of the cartridge buttress member 130, the tensionbeing sufficient to maintain the cartridge buttress member 130 securedto the cartridge body 120. The secondary knife blade 170 includes aknife body 172 that is substantially L-shaped. The knife body 172 hasblade 176 on a distal end portion thereof and a support arm 174 on aproximal end portion thereof. The support arm 174 extends laterally fromthe proximal end portion of the knife body 172 and defines a pair ofopposed recesses 174 a dimensioned to receive the pair of opposed nubs164 (see FIGS. 4 and 5A) of the pusher member 160 to facilitatesecurement of the support arm 174 within the knife supporting slot 162 bof the pusher member 160.

During operation of the surgical stapling device 10, the anvil assembly200 and the cartridge assembly 100 are approximated by the actuation ofadvancing member 22 until the anvil assembly 200 and the cartridgeassembly 100 are suitably clamped against tissue of a patient. Thetrigger member 24 is then actuated to fire the surgical stapling device10. Reference may be made to U.S. Pat. No. 5,915,616 to Viola et al. andU.S. Patent Application Publication No. 2011/0174099 referred to abovefor a detailed description of the use of a surgical stapling device 10in a surgical procedure.

With reference again to FIGS. 4 and 5A, upon a firing of the surgicalstapling device 10, the pusher member 160 is distally advanced from theproximal position (FIG. 4) to the distal position (FIG. 5A) which drivesthe pushers 162 a of the pusher member 160 through the fastenerretaining slots 124 of the cartridge body 120 into engagement with thefasteners 60 to dispense the fasteners 60 from the fastener retainingslots 124.

The distal movement of the pusher member 160 drives the secondary knifeblade 170 distally to severe the retaining ring member 140. Notably,with reference to FIG. 5B, to sever the retaining ring member 140, thesecondary knife blade 170 advances distally through knife slot 156 ofthe stop member 150 and into engagement with a proximal surface of thecross member 158 of the stop member 150 which prevents further distaladvancement of the secondary knife blade 170 after the blade 176 of thesecondary knife blade 170 cuts through the retaining ring member 140. Adistal surface of the stop member 150 including the cross member 158prevents tissue from extruding in front of the secondary knife blade 170when tissue is clamped between the anvil assembly 200 and the cartridgeassembly 100 upon approximation of the anvil assembly 200 and thecartridge assembly 100.

Upon a severing of the retaining ring member 140, the securement tensionimparted to the extension portion 134 of the cartridge buttress member130 by the retaining ring member 140, prior to a severance of theretaining ring member 140, to secure the cartridge buttress member 130to the cartridge assembly 100, is released. When the imparted tension isreleased, the extension portion 134 is freed so that when the device 10is withdrawn from the surgical site, the cartridge buttress member 130remains with the stapled tissue and is separated from cartridge body120.

When the fasteners 60 are dispensed from the fastener retaining slots124, the legs of the fasteners 60 are advanced through the clampedtissue and any buttress material clamped against tissue including thecartridge buttress member 130 and any buttress material that maysupported on the anvil assembly. As the fasteners 60 are distallyadvanced, the legs of the fasteners are formed by fastener formingpockets defined in an anvil plate of the anvil assembly 200 to securethe buttress material including the cartridge buttress member 130 to thetissue.

Simultaneously or thereafter, the knife 52 is driven distally to severthe clamped tissue so that the buttress material is secured to tissueindependent of the circular stapling apparatus 10.

Persons skilled in the art will understand that the structures andmethods specifically described herein and illustrated in theaccompanying figures are non-limiting exemplary embodiments, and thatthe description, disclosure, and figures should be construed merely asexemplary of particular embodiments. It is to be understood, therefore,that the present disclosure is not limited to the precise embodimentsdescribed, and that various other changes and modifications may beeffected by one skilled in the art without departing from the scope orspirit of the disclosure. Additionally, it is envisioned that theelements and features illustrated or described in connection with oneexemplary embodiment may be combined with the elements and features ofanother without departing from the scope of the present disclosure, andthat such modifications and variations are also intended to be includedwithin the scope of the present disclosure. Indeed, any combination ofany of the presently disclosed elements and features is within the scopeof the present disclosure. Accordingly, the subject matter of thepresent disclosure is not to be limited by what has been particularlyshown and described.

What is claimed is:
 1. A circular stapling device, comprising: a handleassembly; an elongate body that extends from the handle assembly; acartridge assembly mounted on a distal end of the elongate body, thecartridge assembly defining an annular containment groove, the cartridgeassembly including: a housing; a pusher member supported within thehousing and being movable between a first position and a secondposition; and a fastener cartridge body supported on the housing andhaving a tissue engaging surface that extends to an annular edge; acircular cartridge buttress member having a body portion and anextension portion, the body portion being supported on the tissueengaging surface of the fastener cartridge body, the extension portionextending from the body portion and over the annular edge of the tissueengaging surface; and a retaining ring member secured within thecontainment groove over the extension portion of the circular cartridgebuttress member to releasably secure the circular cartridge buttressmember to the fastener cartridge body.
 2. The circular staplingapparatus of claim 1, further comprising a knife assembly, the knifeassembly including a primary knife blade and a secondary knife blade,the primary knife blade dimensioned to cut tissue, the secondary knifeblade being connected to the pusher member, the secondary knife bladebeing movable with the pusher member to cut the retaining ring memberand relieve a tension that the retaining ring member exerts on theextension portion of the circular cartridge buttress member, the tensionbeing sufficient to maintain the circular cartridge buttress membersecured to the fastener cartridge body.
 3. The circular staplingapparatus of claim 2, wherein the housing includes at least onecontainment tab that extends distally from a distal end portion of thehousing so that an inner surface of the at least one containment tab isengageable with an outer surface of the retaining ring member tomaintain the retaining ring member secured to the housing after theretaining ring member is cut with the secondary knife blade.
 4. Thecircular stapling apparatus of claim 2, wherein the fastener cartridgebody supports a stop member that defines a receiving channel dimensionedto receive the retaining ring member and a knife slot dimensioned toreceive a distal end portion of the secondary knife blade, the stopmember including a cross member dimensioned to prevent tissue fromextruding in front of the distal end portion of the secondary knifeblade, the distal end portion of the secondary knife blade beingengageable with the cross member upon a translation of the distal endportion of the secondary knife blade through the knife slot.
 5. Thecircular stapling apparatus of claim 4, wherein the stop member isformed of a polyethylene material.
 6. The circular stapling apparatus ofclaim 1, wherein the retaining ring member is an o-ring.
 7. The circularstapling apparatus of claim 6, wherein the o-ring is formed of anelastomeric material.
 8. The circular stapling apparatus of claim 1,wherein the housing and the fastener cartridge body together define thecontainment groove therebetween.
 9. A cartridge assembly, comprising: ahousing; a pusher member supported within the housing and being movablebetween a first position and a second position; and a fastener cartridgebody supported on the housing and having a tissue engaging surface thatextends to an annular edge, wherein at least one of the housing and thefastener cartridge body define an annular containment groove; a circularcartridge buttress member having a body portion and an extensionportion, the body portion being supported on the tissue engaging surfaceof the fastener cartridge body, the extension portion extending from thebody portion and over the annular edge of the tissue engaging surface;and a retaining ring member secured within the containment groove toreleasably secure the extension portion of the circular cartridgebuttress member to the cartridge assembly.
 10. The cartridge assembly ofclaim 9, wherein a knife blade is connected to the pusher member, theknife blade being movable with the pusher member to cut the retainingring member and relieve a tension that the retaining ring member exertson the extension portion of the circular cartridge buttress member, thetension being sufficient to maintain the circular cartridge buttressmember secured to the fastener cartridge body.
 11. The cartridgeassembly of claim 10, further comprising a tissue cutting knife bladedimensioned to cut tissue.
 12. The cartridge assembly of claim 9,wherein the housing includes at least one containment tab that extendsdistally from a distal end portion of the housing so that an innersurface of the at least one containment tab is engageable with an outersurface of the retaining ring member to maintain the retaining ringmember secured to the housing.
 13. The cartridge assembly of claim 10,wherein the fastener cartridge body supports a stop member that definesa receiving channel dimensioned to receive the retaining ring member anda knife slot dimensioned to receive a distal end portion of the knifeblade, the stop member including a cross member dimensioned to preventtissue from extruding in front of the distal end portion of the knifeblade, the distal end portion of the knife blade being engageable withthe cross member upon a translation of the distal end portion of theknife blade through the knife slot.
 14. The cartridge assembly of claim13, wherein the stop member is formed of a polyethylene material. 15.The cartridge assembly of claim 9, wherein the retaining ring member isan o-ring formed of elastomeric material.